METALLURGY OF IRON AFD STEEL.
steel is cooled to a proper casting temperature by the addition of scrap in the ladle, and large quantities of rails and other products have been thus made with from 0.3 to 0.6 per cent, of silicon. Some pig-iron, notably in Germany and Sweden, contains a considerable proportion of manganese; this burns, in some measure, at the same time as the silicon; but when the manganese is present in large quantity, the carbon has preference. In Sweden this fact is made use of in the manufacture of tool steels, the operation being stopped when the bath is high in carbon, the metal still containing a sufficient proportion of manganese to insure good working.
SEC. VId.—Swedish practice.—The Swedish practice has .been discussed by Akerman,* and many of the following statements are founded on his authority. The pig-iron contains not much over 1.0 per cent, of silicon to insure that the product shall be free from this metalloid, even if the blow be interrupted when high in carbon. The charge is taken in a molten state from the blast furnace to the converter, a practice which has been in general use in Sweden since 1857. The slow working and small charges which characterize the
TABLE VI-B. Manganiferous Bessemer Pig-irons.
Name of Works. Sample. Time to beginning of boll. Time of blowing when samples •were taken. Composition of Metal; percent. Composition of Slag; pe'r cent.
C Si Mn SiO, FeO MnO A1203
Langhyt-tan. Pig-iron. Bess, bath « » « « 8.94 4.20 1.10 .05 1.14 .04 .03 .01 .64 .12 .12 .06
2m. 45s. 2m. 16s. 4m. 80s. 5m. 80s. 48.76 59.82 48.48 84.72 21.08 85.82 13.06 15.48 12.29 .78 .98 .72
Ny-kroppa. Pig-iron. 4.85 .88 1.15
Bess, bath it K « <i 1m. 80s. 2m. 80s. 5m. 80s. 6m. 80s. 4.10 1.00 .08 .10 .05 .04 .15 .15 .08 58.26 62.84 44.52 18.50 9.54 80.60 29.76 28.70 21.89 2.28 8.00 2.14
Westanf-ors. Pig-Iron. Bess, bath ti <t <( ti 4.22 4.20 1.80 .55 1.06 .43 .12 .or 5.12 8.26 .85 .43
2m. 80s. 4m. 15s. 8m. 85s. Om. 20s. 46.87 89.07 87.68 4.20 6.24 0.46 46.88 52.26 48.02 8.08 2.49 2.M
Bessemer practice of Sweden render necessary a hot-blowing metal, and since the silicon cannot be high without danger of leaving some in the product, it is customary to have from 1.5 to 4.0 per cent, of
* Bessemer Process as Conducted in Sweden. Trans? A. I. M. J/., ,Tol. XXII, p. 265.